Distress of concrete refers to the deterioration and decomposition of concrete caused by environmental conditions, autogenous internal influences, and exposure to operation services and testing.
Concrete may suffer from several types of distresses, such as delamination, chalking, crack, and flaking, that must be accurately described and identified in the visual inspection report. This helps engineers and contractors choose suitable repair materials and follow proper procedures.
How to Describe Concrete Distress in Visual Inspection Report?
1. Chalking
Loose powder formed due to concrete surface disintegration or application of coating like cementitious coating.
2. Curling
Distortion of a concrete member from its original shape, such as warping of the slab because of the differences in temperature and moisture content in zones adjacent to opposite faces.
3. Deflection
Deflection is the movement of a point on a structural element with respect to a reference axis, measured as a linear displacement.
4. Deformation and Distortion
Distortion is a change in the shape or dimension of a concrete member.
5. Delamination
Delamination is the separation of concrete along a plane parallel to a surface. It is similar to scaling and peeling, but affects larger areas. Tapping or chain dragging can be used to detect the delamination of concrete.
6. Disintegration
Disintegration is the reduction of concrete into small fragments and ultimately into particles due to erosion, abrasion, cavitation, biological attack, and chemical attack.
7. Drummy Area
Drummy area in concrete structure releases hollow sound under the concrete layer because of a void, which is the result of poor consolidation, or delamination.
8. Efflorescence
Efflorescence is a white salt formed on a concrete surface. Salt solution migrates within concrete or masonry to the surface, precipitating due to a reaction like the evaporation of carbonation.
9. Exudation
Exudation is the discharge of liquid or viscous gel-like material through a pore, crack, or opening in the surface of the concrete.
8. Exfoliation
Exfoliation is the disintegration of concrete by peeling off in a successive layer, swelling up, and opening into a plate or leaves like a partially opened book.
9. Joint Deficiencies
Joint deficiencies include spall of concrete adjacent to a joint, cracked or debonded joint sealant, leading to the opening of a joint, joint leakage due to movement of liquid through a joint, and joint fault due to differential displacement of a part of a structure along a joint.
10. Leakage
Leakage is the migration of contained material like liquid and gas through concrete.
11. Mortar Flaking
Mortar flaking is a form of scaling over coarse aggregate.
12. Peeling
Peeling is the breakaway of thin flakes of mortar from a concrete surface due to deterioration or adherence of mortar to forms during stripping process.
13. Pitting
Pitting is the formation of fairly small cavities on a concrete surface, i.e., localized disintegration like popout and localized corrosion evident as minute cavities on the concrete surface.
14. Popout
Popout is the breakaway of a small part of a concrete surface because of localized internal pressure that creates a shallow, typically conical depression with broken coarse aggregate at the bottom.
15. Scaling
Scaling is localized flaking or peeling away of the near-surface part of hardened concrete or mortar, and it is classified as light, medium, severe, and very severe scaling, see Figure-18.
Light scaling does not lead to aggregate exposure, whereas medium concrete loss from 5 mm to 10 mm surface mortar and its aggregate can be seen.
Severely scaled concrete loses some aggregate particles and mortar around aggregate to a depth of around 5 mm 10 mm. It is considered severely scaled if a concrete loses aggregate and surface mortar to a depth of around 20 mm.
16. Spalling
Spalling is a fragment of concrete separated from concrete elements due to blow, the action of weather, fire, pressure, and expansion within a larger mass.
A small spall is a fairly circular depression on a concrete surface with 20 mm depth and 150 mm in any dimension.
Regarding large spall, the shape can be roughly circular, oval, and sometimes elongated with a depth of larger than 20 mm and 150 mm in any dimension.
FAQs
Visual inspection is an exploration of the concrete surfaces to specify different deterioration that a concrete element may experience during its service life.
Chalking is a loose powder formed due to concrete surface disintegration or applied coating like cementitious coating.
Tapping or chain dragging can be used to detect the delamination of concrete.
1. Erosion
2. Abrasion
3. Cavitation
4. Biological attack
5. Chemical attack
A small spall is a fairly circular depression on a concrete surface with 20 mm depth and 150 mm in any dimension. Regarding large spall, the shape can be roughly circular, oval, and sometimes elongated with a depth of larger than 20 mm and 150 mm in any dimension.
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